Range Of Velocities Research Articles

CLASSY. X. Highlighting Differences between Partial Covering and Semianalytic Modeling in the Estimation of Galactic Outflow Properties

Feedback-driven massive outflows play a crucial role in galaxy evolution by regulating star formation and influencing the dynamics of surrounding media. Extracting outflow properties from spectral lines is a notoriously difficult process for a number of reasons, including the possibility that a substantial fraction of the outflow is carried by dense gas in a very narrow range in velocity. This gas can hide in spectra with insufficient resolution. Empirically motivated analysis based on the apparent optical depth method, commonly used in the literature, neglects the contribution of this gas, and may therefore underestimate the true gas column density. More complex semianalytical line transfer (e.g., SALT) models, on the other hand, allow for the presence of this gas by modeling the radial density and velocity of the outflows as power laws. Here we compare the two approaches to quantify the uncertainties in the inferences of outflow properties based on 1D “down-the-barrel” spectra, using the UV spectra of the CLASSY galaxy sample. We find that empirical modeling may significantly underestimate the column densities relative to SALT analysis, particularly in the optically thick regime. We use simulations to show that the main reason for this discrepancy is the presence of a large amount of dense material at low velocities, which can be hidden by the finite spectral resolution of the data. The SALT models in turn could overestimate the column densities if the assumed power laws of the density profiles are not a property of actual outflows.

Nonlinear vibrations and static bifurcation of a hyperelastic pipe conveying fluid

This study investigates the free and forced nonlinear vibrations, along with the static bifurcation behavior, of a fluid transmission hyperelastic pipe supported by clamped ends. Both geometrical and material nonlinearities are taken into account. The mathematical model is grounded in Euler–Bernoulli beam theory, incorporating von Kármán nonlinearity to capture the complexities of the system. For the hyperelastic materials, the strain energy function proposed by Yeoh is employed. Considering that the lowest critical velocity of the fluid flow is associated with the first mode, after deriving the governing equation using Hamilton’s principle, Galerkin discretization is applied to obtain the reduced order model in the first mode. Analysis of static bifurcation and stability is performed and critical velocity values of fluid flow are determined. The analysis of free and forced vibrations of the hyperelastic pipe is conducted using the method of multiple time scales, specifically focusing on the sub-critical velocity range of fluid flow, which corresponds to the unbuckled state of the pipe. This approach allows for a comprehensive examination of how fluid flow velocity influences the frequency characteristics of free vibrations, as well as the frequency response in the vicinity of the main resonance. The results obtained from this study can significantly enhance our understanding of the design and application of hyperelastic pipes in various fluid transfer scenarios. By elucidating the dynamic behavior and critical parameters associated with these pipes, the findings can inform engineering practices and contribute to the optimization of systems that utilize hyperelastic materials for fluid conveyance.

The Effect of Velocity-Based Training on Some Performance Parameters in Football Players

The aim of the study was to investigate the effects of velocity-based (VBT) and traditional strength training (TST) methods on vertical jump, dynamic balance, agility, 10 m acceleration and 20 m sprint performances. Twelve volunteer men randomly divided into two groups participated in the study. After 1 Repetition Maximum (1RM) was determined, the TST group performed 3 sets of 10 repetitions with 40-60% of their maximum weight, while the VBT group performed 3 sets of strength training at a velocity range of 0.75-1.0 m/s for 6 weeks, 2 days a week. In the VBT group, a significant difference was found between 55.16±6.17 cm in the pre-test and 59.16±4.99 cm in the post-test of vertical jump and 4.05±0.27 in the pre-test and 1.72±0.27 in the post-test of balance (p<0.05). There was a significant difference between 48.33±3.98 cm in the pre-test and 53.66±4.03 cm in the post-test; between 4.29±0.29 in the pre-test and 3.65±0.48 in the post-test. Optimising the speed while lifting load in VBT enables athletes to react faster to sudden position changes by improving dynamic balance. Although 6 weeks of VBT training increased vertical jump, the difference was not statistically significant, which may be due to sample size, training duration or individual differences. As a result, the increase in vertical jump and balance in both strength training exercises can be explained by the fact that squat exercise activates the quadriceps muscles by activating the knee joint and increases leg strength, endurance and knee stabilisation.

Glacial lake outburst flood risk assessment of a rapidly expanding glacial lake in the Ladakh region of Western Himalaya, using hydrodynamic modeling

The ongoing trend of warming climate has made Glacial Lake Outburst Floods (GLOFs) a major cryospheric hazard worldwide, especially in the Himalayas. GLOFs in the Himalayan region are mostly caused by moraine-dammed proglacial lakes and ice-dammed lakes. These sporadic disasters have resulted in significant loss of life and property. This study offers a comprehensive analysis of the GLOF hazard potential of a potentially dangerous proglacial lake (PDGL) in the Ladakh region. This research explores the GLOF threat from the lake using multi-criteria analysis and advanced 2D hydrodynamic modeling approaches. The mass balance response of the mother glacier, its flow dynamics, and glacier-lake interactions were examined for the past 22 years. The findings show that over this period, the PDGL has had a notable expansion of 78.7%, accompanied by a significant recession of 13.2% in its feeding glacier. The glacier has witnessed an average thickness loss of ⁓7 m at the rate of 0.32 m a−1 during this period. The average, lowest, and maximum depth of the glacier were found to be 30.95, 14.30, and 50.57 m, respectively and the average velocity of the glacier was estimated as 3.38 m a−1. Because of the lake’s rapid expansion and steep surrounding slopes, it was classified as a high-hazard lake. The risk to the downstream community was assessed through 2D hydrodynamic modeling using the HEC-RAS tool. The maximum discharge under the worst-case scenario for the piping and overtopping failures was estimated as 3890.99 m3s−1 and 5111.39 m3s−1, respectively. The area potentially under the threat of inundation was calculated to be 4.74 and 5.38 km2 for the moderate and worst-case scenarios respectively. The expected maximum flood velocities range from 18.26 to 23.78 meters, respectively for the moderate and worst-case scenarios. At several locations in the downstream area, routed hydrographs representing the GLOF propagation were generated. The findings show that the flood wave in the worst-case scenario would arrive at the first settlement in 50 min, with a peak velocity of 12.36 m s−1. The potentially inundated area includes critical infrastructure such as bridges, residential houses, and roads. To mitigate the potential risk associated with this lake, a more detailed and on-site study is highly recommended.

Aerodynamic analysis and hygrothermal transfer characteristics of cellulose evaporative cooling pads: A case study applied to protected agriculture

Evaporative cooling pads are clean media for cost-effective temperature management. However, the spatially integrated microclimate resulting from heat and mass transfer in the evaporative cooling pad is an uncertain and nonlinear complexity. Therefore, this purpose of this study is to present an innovative prediction model with computational fluid dynamics and evaluate the operating scenarios and geometrical properties of wet pads from quantitative metrics such as saturation efficiency and pressure drop. The reliability of the established numerical model of wet pads was verified by wind tunnel experiments and existing experiments, which predicted the outlet conditions in satisfactory conformity. The results showed that a wet pad with 8 mm ripple height and 19.6 mm ripple distance exhibits the best prospective, with energy consumption and specific water consumption reduced by 45.28 % and 26.26 %, respectively. Meanwhile, the cross strategy of 45_45° corrugation obliquity reduces the pressure drop by 18.95 %, providing uniform supply air distributions. The heat exchange of the wet pad is mainly concentrated within the first 35 mm from the inlet section, while the mass exchange of the wet pad is concentrated within the first 60 mm. The range of frontal air velocity with 0.9–2.5 m/s is recommend for the evaporative cooling system.

What is Light, Really? A Quantum Dialectical View

Radiant energy in the form of visible light has been and still remains the most mysterious and venerated object in human history. Gradual understanding of the nature of light now in its very wide range of energy, both above and below the visible range; has led to the proliferation of technologies, especially after the recognition of its quantum nature. Although impressive knowledge about the nature of light, its properties, its source, and its interaction with other existing matter, etc., have been gained and profitably utilized in technologies; its fundamental unit as a discrete point particle or an extended continuous wavelet, as well as its mass, still remains a subject of intense debate among the physicists. Understanding the enigmatic properties and the nature of light as difficult as it proved to be; understanding the velocity of its propagation proved to be the most misunderstood aspect of light. As has been shown through some recent publications by this author, the false axiomatic notion of Albert Einstein at the turn of the 20th century, about the universal and absolute constancy (in vacuum) of the velocity c of light; caused the century-long confusion, paradoxes, myths and ironically, the darkest period of modern physics and cosmology! Another wrong centuries-old axiomatic notion of Isaac Newton about the one-sided universal gravitational attraction of matter, acted in a synergistic way with Einstein’s false axiomatic notion about light; to create the modern and sophisticated ruling mythology of the “Big Bang” creation of the universe, undermining scientific progress both in theoretical physics and in cosmology, since Copernicus and Johannes Kepler. It can now be demonstrated that this new mythology has absolutely no basis in objective reality and is the product of brain-cooked and abstract mathematical fabrications based on an axiomatic truth and apparently willful deceptions by official science. A quantum dialectical approach reveals that light is composed of point particles (photons) with a wide range of energy, velocity, and mass; over the whole electromagnetic spectrum, from the microwave to the highest energy gamma-ray photons. The only difference from other matter particles is that photons exist only in their free elementary state and are created instantly (until absorbed) from their virtual existence in matter atoms or in the quantum vacuum; in this infinite, eternal, and ever-changing universe; thereby resolving all mysteries about light.

Influence of Binding Energies on Required Process Conditions in Aerosol Deposition

AbstractWith the high interest in aerosol deposition in order to form high-quality coatings by solid-state impact, there is an increasing demand for developing general guidelines to estimate needed particle velocities and thus process parameter sets for successful deposition of ceramic materials. By using modeling approaches, rather different material properties in first instance can be expressed in terms of binding energies. Needed velocities for possible bonding can then derived by impact simulations and compared to experimental results from the literature. In order to study the role of binding energy on the impact behavior of ceramic particles in aerosol deposition, a molecular dynamics study is presented. Single-particle impacts are simulated for a range of binding energies, particle sizes and impact velocities. The results show that increasing the binding energy from 0.22 to 0.96 eV results in up to three times higher characteristic velocities corresponding to the threshold of bonding or grain size-dependent fragmentation of the particles. However, regardless of the binding energy, exceeding the characteristic velocities results in a similar deformation and fragmentation pattern. This allows for a general representation of the impact behavior as a function of normalized impact velocity for different ceramic materials. Apart from dealing with prerequisites for bonding of different materials by aerosol deposition, this study could also be generally relevant to the high-velocity deformation behavior of ceramics with different grain sizes.

Lie-theory-based dynamic model identification of serial robots considering nonlinear friction and optimal excitation trajectory

Abstract Accurate dynamic model is essential for the model-based control of robotic systems. However, on the one hand, the nonlinearity of the friction is seldom treated in robot dynamics. On the other hand, few of the previous studies reasonably balance the calculation time-consuming and the quality for the excitation trajectory optimization. To address these challenges, this article gives a Lie-theory-based dynamic modeling scheme of multi-degree-of-freedom (DoF) serial robots involving nonlinear friction and excitation trajectory optimization. First, we introduce two coefficients to describe the Stribeck characteristics of Coulomb and static friction and consider the dependency of friction on load torque, so as to propose an improved Stribeck friction model. Whereafter, the improved friction model is simplified in a no-load scenario, a novel nonlinear dynamic model is linearized to capture the features of viscous friction across the entire velocity range. Additionally, a new optimization algorithm of excitation trajectories is presented considering the benefits of three different optimization criteria to design the optimal excitation trajectory. On the basis of the above, we retrieve a feasible dynamic parameter set of serial robots through the hybrid least square algorithm. Finally, our research is supported by simulation and experimental analyses of different combinations on the seven-DoF Franka Emika robot. The results show that the proposed friction has better accuracy performance, and the modified optimization algorithm can reduce the overall time required for the optimization process while maintaining the quality of the identification results.

Optimizing the Pore Structure of Lotus-Type Porous Copper Fabricated by Continuous Casting.

Lotus-type porous copper was fabricated using a continuous casting method in pressurized hydrogen and nitrogen gas atmospheres. This study evaluates the effects of process parameters, such as the hydrogen ratio, total pressure, and transference velocity, on the resulting pore structure. A continuous casting process was developed to facilitate the mass production of lotus-type porous copper. To achieve the desired porosity and pore diameter for large-scale manufacturing, a systematic evaluation of the influence of each process parameter was conducted. Lotus-type porous copper was produced within a hydrogen ratio range of 25-50%, a transference velocity range of 30-90 mm∙min-1, and a total pressure range of 0.2-0.4 MPa. As a result, the porosity ranged from 36% to 55% and the pore size varied from 300 to 1500 µm, demonstrating a wide range of porosities and pore sizes. Through process optimization, it is possible to control the porosity and pore size. The hydrogen ratio and total pressure were found to primarily affect porosity, whereas the hydrogen ratio, transference velocity, and total pressure significantly influenced pore diameter. When considering these parameters together, porosity was most influenced by the hydrogen ratio, whereas the total pressure and transference velocity had a greater influence on pore diameter. Reducing the hydrogen ratio and increasing the transference velocity and total pressure reduced the pore diameter and porosity. This optimization of the continuous casting process enables the control of porosity and pore diameter, facilitating the production of lotus-type porous copper with the desired pore structures.

Elastic and radiation shielding properties of zinc borotellurite glass systems: The impact of gadolinium oxide

Using the formula [(TeO2)70(B2O3)30], this study examines the impact of Gd2O3 on the elasticity and radiation shielding characteristics of zinc borotellurite glass. Glass samples containing 1–5% mol% Gd2O3 were created by employing the melt quench technique. XRD verified that they are amorphous in nature, and the existence of TeO3, TeO4, BO3, and BO4 vibrational groups was revealed by infrared spectra. The structural alterations were shown by the range of longitudinal and shear ultrasonic velocities, which were 3908–4076 m/s and 2222–2277 m/s, respectively. The glass's rigidity was improved by the large rise in elastic moduli, such as bulk (45 GPa), longitudinal (80 GPa), shear (25 GPa), and Young's moduli (60 GPa), with a higher Gd2O3 content. Higher concentrations of Gd2O3 resulted in a rise in the mass attenuation coefficient (μρ), as measured by WinXcom, which enhanced gamma-ray shielding. The half-value layer (HVL) and mean free path (MFP) at 0.662 MeV decreased with increasing Gd2O3 in a consistent manner. The maximum density and optimum gamma-ray shielding performance were found in the glass containing 5 mol% Gd2O3. These results show Gd2O3 for applications needing greater rigidity and better radiation protection by demonstrating how it affects the elastic and radiation-shielding efficiency of the glass network.

Spark ignition and stable flame of premixed methanol-ammonia gaseous jet at atmospheric surrounding

Ammonia, regarded as a zero-carbon fuel, presents significant challenges due to its notable combustion and chemical inertness. To mitigate these challenges, blending liquid ammonia with carbon-neutral methanol offers a promising avenue for creating an innovative, stable, and large-scale producible carbon-neutral fuel. This study investigates the impacts of xCH3OH (methanol mole ratio in methanol-ammonia mixture) and v (mean jet velocity at nozzle outlet) on forming stable flames of a premixed methanol-ammonia argon-oxygen (MA-AO) gaseous jet in the atmospheric surrounding. Results indicate that the pure ammonia argon-oxygen (A-AO) mixture can be ignited by an electrical spark with the energy of about 52.1 mJ, but it cannot grow to be a stable jet flame although the fire nucleus can form. Blending methanol is very helpful in forming a stable jet flame of the MA-AO mixture. When xCH3OH is lower than 49% at λ = 1.0, only the fire nucleus could be formed without a stable jet flame. When xCH3OH is more than 49%, there is a certain mean jet velocity range for different xCH3OH to form a stable flame. At the low-velocity limit, the flame would be quenching. While the flame would be blown off at the high-velocity limit. The velocity limits of quenching and blow-off become higher with higher xCH3OH, and the blow-off velocity limit increases more evident.

Determining the Fish Migration Patterns Based on Fish Habitat Assessment at a River Confluence

ABSTRACTMuch effort has been devoted to predicting fish migration routes to assist target species migration, and yet, fish migration science and practice remain imperfect. This study aimed to predict the migration paths of Gymnocypris przewalskii at the river confluence in the Qinghai Lake basin. The authors proposed an approach for fish migration route prediction, which involves a hydrodynamic module, a habitat model and a fish migration module. The TELEMAC‐MASCARET system was used to simulate hydrodynamic conditions and statistical analyses were carried out. During the flood season, G. przewalskii migrates downstream, whereas during the migratory season, they migrate upstream. The results indicate that flow velocity was the most significant hydrodynamic parameter affecting fish migration behaviour. The optimal flow velocity range for the target fish species was between 0.7 and 1.7 m/s. The impact of water depth was only observed in low discharge situations. Besides, the temperature plays a vital role in determining fish migration and abundance. However, the results reveal that in the morning hours, the temperature exhibits a range of 10°C to 16°C, and in the noon, the average temperature ranges from 16°C to 19°C, with a maximum temperature reaching 23°C. These temperature variations enable fish to migrate towards the tributary offering a more favourable water temperature during route selection at a river confluence. The study concludes that future research should consider incorporating the swimming capacity of the focal fish species to provide insights into fish migration patterns.

The outcome of collisions between gaseous clumps formed by disk instability

The disk instability model is a promising pathway for giant planet formation in various conditions. At the moment, population synthesis models are used to investigate the outcomes of this theory, where a key ingredient of the disk population evolution are collisions of self-gravitating clumps formed by the disk instabilities. In this study, we explored the wide range of dynamics between the colliding clumps by performing state-of-the-art smoothed particle hydrodynamics simulations with a hydrogen-helium mixture equation of state and investigated the parameter space of collisions between clumps of different ages, masses (1--10 Jupiter mass), various impact conditions (head-on to oblique collisions) and a range of relative velocities. We find that the perfect merger assumption used in population synthesis models is rarely satisfied and that the outcomes of most of the collisions lead to erosion, disruption or a hit-and-run. We also show that in some cases collisions can initiate the dynamical collapse of the clump. We conclude that population synthesis models should abandon the simplifying assumption of perfect merging. Relaxing this assumption will significantly affect the inferred population of planets resulting from the disk instability model.

Numerical simulation of falling film dehumidification with rectangular cylinder insertion modification at different elevations

ABSTRACT A falling film dehumidifier is one type of desiccant-based dehumidifier with superior performance and has a simple design and working mechanism. Geometric modifications of falling film dehumidifiers can impact their fluid flow and effectiveness. For further investigations, a CFD (Computational Fluid Dynamics) numerical simulation was carried out on the dehumidifier geometric innovation equipped with a rectangular cylinder with variations in different height positions. Falling film dehumidifier with four variations of rectangular cylinder height positions (3/12 h, 5/12 h, 7/12 h, and 9/12 h) was analyzed to determine its impact on dehumidification performance for each incoming airflow of 0.5 m/s, 1 m/s, and 1.5 m/s. Based on the results, it was evident that adding a rectangular cylinder to the humid air passage can change the flow characteristics, enhance the distribution rate of mass and air temperature, and ultimately enhance the dehumidification performance. The decrease in humidity and temperature increased by 11–14% and 11–27%, respectively, for the air velocity range of 0.5–1.5 m/s. In addition, the dehumidification performance was obtained to increase by 11–14% at the same air velocity range. Variations in the position of a rectangular cylinder show different results, where the lowest position delivers the best dehumidification performance.

Interpretation of possible biogas production capacity by investigating the effects of anaerobic digester tank geometry and angular velocity on flow characteristics.

Mixing performance in reactors producing biogas through anaerobic digestion is one of the parameters that directly affect biogas yield. The most commonly used mixing model for bioreactors in biogas-production processes is mechanical mixing. In the present study, we focus on the geometry of the tank, where the mechanical mixing actually takes place. In this context, by using the six-blade standard Rushton impeller in two different types of tank, flow patterns involving velocity, dead zone volume, turbulent kinetic energy, and turbulent eddy dissipation rate in the angular velocity range of 25-100rpm were observed, and the possible effects of the results on biogas production were interpreted. A new impeller design was proposed that maximizes the interface between the fluid inside the reactor tank and the impeller, which has the potential to reduce the dead zone volume to significantly lower levels. Our results showed that the lowest dead zone volume was achieved for a 60° slope reactor tank compared to the conventional 90° slope reactor tank at an angular velocity of 100rpm. The dead zone volume decreased to 0.000094 m3 at 100rpm in the 60° slope reactor tank with a total volume of 0.0305 m3, which by comparison was 0.000374 m3 in the 90° slope reactor tank. The magnitudes of both maximum turbulent kinetic energy and maximum turbulent eddy dissipation were higher in the 60° slope reactor tank at all angular velocities examined, which would be expected to enhance mixing performance. It is hoped that the reader will benefit from the results of this study; however, further studies should be conducted on the use of actual biowaste as the working fluid instead of water.

Validity and Concordance of a Linear Position Transducer (Vitruve) for Measuring Movement Velocity during Resistance Training.

This study aimed to analyze the intra-device agreement of a new linear position transducer (Vitruve, VT) and the inter-device agreement with a previously validated linear velocity transducer (T-Force System, TF) in different range of velocities. A group of 50 healthy, physically active men performed a progressive loading test during a bench press (BP) and full-squat (SQ) exercise with a simultaneous recording of two VT and one TF devices. The mean propulsive velocity (MPV) and peak of velocity (PV) were recorded for subsequent analysis. A set of statistics was used to determine the degree of agreement (Intraclass correlation coefficient [ICC], Lin's concordance correlation coefficient [CCC], mean square deviation [MSD], and variance of the difference between measurements [VMD]) and the error magnitude (standard error of measurement [SEM], smallest detectable change [SDC], and maximum errors [ME]) between devices. The established velocity ranges were as follows: >1.20 m·s-1; 1.20-0.95 m·s-1; 0.95-0.70 m·s-1; 0.70-0.45 m·s-1; ≤0.45 m·s-1 for BP; and >1.50 m·s-1; 1.50-1.25 m·s-1; 1.25-1.00 m·s-1; 1.00-0.75 m·s-1; and ≤0.75 m·s-1 for SQ. For the MPV, the VT system showed high intra- and inter-device agreement and moderate error magnitude with pooled data in both exercises. However, the level of agreement decreased (ICC: 0.790-0.996; CCC: 0.663-0.992) and the error increased (ME: 2.8-13.4% 1RM; SEM: 0.035-0.01 m·s-1) as the velocity range increased. For the PV, the magnitude of error was very high in both exercises. In conclusion, our results suggest that the VT system should only be used at MPVs below 0.45 m·s-1 for BP and 0.75 m·s-1 for SQ in order to obtain an accurate and reliable measurement, preferably using the MPV variable instead of the PV. Therefore, it appears that the VT system may not be appropriate for objectively monitoring resistance training and assessing strength performance along the entire spectrum of load-velocity curve.

Active control of transonic airfoil flutter using synthetic jets through deep reinforcement learning

This paper presents a novel framework for the active control of transonic airfoil flutter using synthetic jets through deep reinforcement learning (DRL). The research, conducted in a wide range of Mach numbers and flutter velocities, involves an elastically mounted airfoil with two degrees of freedom of pitching and plunging oscillations, subjected to transonic flow conditions at varying Mach numbers. Synthetic jets with zero-mass flux are strategically placed on the airfoil's upper and lower surfaces. This fluid–structure interaction (FSI) problem is treated as the learning environment and is addressed by using the arbitrary Lagrangian–Eulerian lattice Boltzmann flux solver (ALE-LBFS) coupled with a structural solver on dynamic meshes. DRL strategies with proximal policy optimization agents are introduced and trained, based on the velocities probed around the airfoil and the dynamic responses of the structure. The results demonstrate that the pitching and plunging motions of the airfoil in the limited cycle oscillation (LCO) can be effectively alleviated across an extended range of Mach numbers and critical flutter velocities beyond the initial training conditions for control onset. Furthermore, the aerodynamic performance of the airfoil is also enhanced, with an increase in lift coefficient and a reduction in drag coefficient. Even in previously unseen environments with higher flutter velocities, the present strategy is achievable satisfactory control results, including an extended flutter boundary and a reduction in the transonic dip phenomenon. This work underscores the potential of DRL in addressing complex flow control challenges and highlights its potential to expedite the application of DRL in transonic flutter control for aeronautical applications.

Vibration and Noise of Diesel Engine Using Calophyllum inophyllum Biodiesel and MoO3 Nanoparticles: Experimental and Machine learning study

The current study deals with the evaluation of vibrations and noise generated by a diesel engine powered by Calophyllum inophyllum biodiesel blend (B20) and molybdenum trioxide (MoO3) nanoparticles, predicted using machine learning algorithms. The nanoparticles were spread out in B20 at a level of 75 ppm, along with a surfactant and a dispersant to make sure they mixed evenly with the fuel samples. The stability of the nanoparticles was then tested using the principle of photo spectroscopy and it was found that the stability of nanoparticles to which surfactants and dispersants had been added was increased. The experiment with the diesel engine was carried out to evaluate the vibrations and noise by varying different loads (3, 6, 9, and 12 kgf) and injection pressures (200, 220, and 240 bar). The vibrations and noise intensity were reduced with B20 compared to normal diesel and a further reduction was observed by adding nanoparticles together with the dispersant. With increasing load, the RMS velocity and the RMS noise also increased, but these decreased with increasing injection pressure. The most favourable result for RMS velocity and RMS noise was B20+MoO3 75ppm+ Dispersant 75ppm. At an injection pressure of 240 bar and a full load of 12 kgf, the RMS velocity was 0.568 m/s and 55.265 dB, which corresponds to an improvement of 28.76% and 9.78% respectively compared to conventional diesel for B20+MoO375ppm+ Dispersant 75ppm. Finally, the entire experimental data of 60 were predicted using various machine learning (ML) algorithms, such as Random Forest (RF), Decision Trees (DT), Artificial Neural Networks (ANNs), Support Vector Machines (SVM) and XG Boost and the predicted results correlated well with the experimental values. All algorithms have shown a good association, but XGBoost has shown a better correlation coefficient (R2). The R2 of each algorithm is in the range of 0.94-0.99, the MRE and RSME are also in the significant range for both RMS velocity and RMS noise.

Multiple-arc cylinder under flow: Vortex-induced vibration and energy harvesting

The shape of a cylindrical cross-section affects the vibrational performance. The vortex-induced vibration (VIV) phenomena of multiple-arc cylinders were numerically investigated to assess their impact on hydrodynamic energy harvesting and potential vibration suppression across a flow velocity range of 0.2 m/s to 1.4 m/s (1.767×104<Re<1.237×105). The study involves five types of multiple-arc cylinders: 4-arc, 8-arc, 16-arc, 24-arc, and circular cylinders. The accuracy of the numerical method was validated through comparison with experimental data. Specifically, increasing the number of arcs generally enhances overall energy conversion efficiency. Then, the VIV response and energy conversion results of the 24-arc cylinder are similar to those of the circular cylinder with maximum efficiency. Notably, the 4-arc cylinder achieves a global maximum amplitude of 0.074 m (A*=0.83) and a power output of 4.4 W with the new P+T mode, making it the most effective configuration for flow velocities between 0.7 and 0.9 m/s. For vibration suppression of multiple-arc cylinders, the appropriate arc structure effectively reduces amplitudes. The small vortices generated by the arc structures disrupt the separation of normal vortices from the boundary layer, leading to approximately a 50% reduction in amplitude responses for 8-arc and 16-arc cylinders.

Quantifying Normal Diaphragmatic Motion and Shape and their Developmental Changes via Dynamic MRI

BackgroundThe diaphragm is a critical structure in respiratory function, yet in-vivo quantitative description of its motion available in the literature is limited. Research QuestionHow to quantitatively describe regional hemi-diaphragmatic motion and curvature via free-breathing dynamic magnetic resonance imaging (dMRI)? Study Design and MethodsIn this prospective cohort study we gathered dMRI images of 177 normal children and young adults and segmented hemi-diaphragm domes in end-inspiration and end-expiration phases of the constructed 4D image. We selected 25 points uniformly located on each 3D hemi-diaphragm surface. Based on the motion and local shape of hemi-diaphragm at these points, we computed the velocities and sagittal and coronal curvatures in 13 regions on each hemi-diaphragm surface and analyzed the change in these properties with age and sex. ResultsOur cohort consisted of 94 Females, 6-20 years (12.09+3.73), and 83 Males, 6-20 years (11.88+3.57). We observed velocity range: ∼2mm/s to ∼13mm/s; Curvature range – Sagittal: ∼3m-1 to ∼27m-1; Coronal: ∼6m-1 to ∼20m-1. There was no significant difference in velocity between sexes, although the pattern of change in velocity with age was different for the two groups. Strong correlations in velocity were observed between homologous regions of right and left hemi-diaphragms. There was no significant difference in curvatures between sexes or change in curvatures with age. InterpretationRegional motion/curvature of the 3D diaphragmatic surface can be estimated using free-breathing dynamic MRI. Our analysis sheds light on here-to-fore unknown matters such as how the pediatric 3D hemi-diaphragm motion/shape varies regionally, between right and left hemi-diaphragms, between sexes, and with age.